21,742 research outputs found
Full QED+QCD Low-Energy Constants through Reweighting
The effect of sea quark electromagnetic charge on meson masses is
investigated, and first results for full QED+QCD low-energy constants are
presented. The electromagnetic charge for sea quarks is incorporated in
quenched QED+full QCD lattice simulations by a reweighting method. The
reweighting factor, which connects quenched and unquenched QED, is estimated
using a stochastic method on 2+1 flavor dynamical domain-wall quark ensembles.Comment: 5 pages, 9 figures, REVTeX 4.1, v2: published versio
Isospin Breaking Corrections to the HVP with Domain Wall Fermions
We present results for the QED and strong isospin breaking corrections to the
hadronic vacuum polarization using Domain Wall fermions. QED is
included in an electro-quenched setup using two different methods, a stochastic
and a perturbative approach. Results and statistical errors from both methods
are directly compared with each other.Comment: 8 pages, 6 figures, presented at the 35th International Symposium on
Lattice Field Theory (Lattice 2017), Granada, Spain, June 18-24, 201
Calculation of quasi-degenerate energy levels of two-electron ions
Accurate QED calculations of the interelectron interaction corrections for
the , two-electron configurations for ions
with nuclear charge numbers are performed within the line
profile approach. Total energies of these configurations are evaluated.
Employing the fully relativistic treatment based on the {--} coupling
scheme these energy levels become quasi-degenerate in the region . To
treat such states within the framework of QED we utilize the line profile
approach. The calculations are performed within the Coulomb gauge.Comment: 22 pages, 11 figure
Nova regulacijska shema
We develop the mode-matching regularization scheme particularly suitable for problems in a uniform magnetic field. We apply this regularization scheme to bare QED vacuum in (2+1) dimensions. This regularization scheme gives the exact renormalization of the bare QED vacuum and establishes its diamagnetic nature.Razvili smo regulacijsku shemu s usklađivanjem modova koja je posebno pogodna za probleme u jednolikom magnetskom polju. Primijenili smo je u prostoru s (2+1) dimenzija i čistom QED vakuumu. Ova regulacijska shema daje egzaktnu renormalizaciju čistog vakuuma i utvrđuje njegovu dijamagnetsku narav
Considerations Concerning the Radiative Corrections to Muon Decay in the Fermi and Standard Theories
The FAC, PMS, and BLM optimization methods are applied to the QED corrections
to the muon lifetime in the Fermi V-A theory. The FAC and PMS scales are close
to m_e, while the BLM scale nearly concides with the geometric average
\sqrt{m_e m_\mu}. The optimized expressions are employed to estimate the third
order coefficient in the \alpha(m_\mu) expansion and the theoretical error of
the perturbative series. Using arguments based on effective field theory and a
simple examination of Feynman diagrams, it is shown that, if contributions of
O(\alpha m_\mu^2/M_W^2) are neglected, the corrections to muon decay in the SM
factorize into the QED correction of the Fermi V-A theory and the electroweak
amplitude g^2/(1-\Delta r), both of which are strictly scale-independent. We
use the results to clarify how the QED corrections to muon decay and the Fermi
constant G_F should be used in the SM, and what is the natural choice of scales
if running couplings are employed.Comment: 11 pages, latex, no figures To be published in Nucl. Phys.
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